Variable pitch propeller



Filed June 26, 1936 2 Sheets-Sheet l mvzufon ATTORNEYS April 13, 1939.P. HORROCKS VARIABLE PITCH PROPELLER I Filed June 26,-1936 2 Sheets-Sheet 2 uronnevs Patented Apr. 18, 1939 UNITED STATES PATENT OFFICE.

vsnmnm Prrcn PROPEILEB r Percy Hot-rocks, Hyde Park, 1v. Y. ApplicationJune at, 1936, Serial No. 81,500

3 Claims. (01. 170-163) The present invention relates to aircraftpropellers and more particularly to mechanisms associated with apropeller bywhich the pitch of the blades thereof may be varied.

The primary object of the inventionis to pro- -vide a simple and ruggedmechanism of a minimum number of parts adapted for construction withinthe hub of a propeller whereby the blade pitch may be adjusted to anydesired angle at the will of the pilot.

Another object resides in the novel arrangement of certain elements ofthe mechanism comprising the invention which, in addition to providingblade pitch varying means, affords reinforcing members for the propellerblades so as, during rotation of the propeller, to counteract thecentrifugal force and bending stresses imparted to the blades.

A further object of the invention is to provide a propeller pitch changeactuating mechanism,

the same being particularly adapted for symmetrical arrangement aboutthe axis of rotation of the propeller thereby obviating'the occurrenceof vibration and other such detrimental reactions re- 35 sulilzing fromhigh speed operation of the prope er.

The invention will be fully and comprehensively understood from aconsideration of the following detailed description when read inconnection 30 with the accompanying drawings which form part of theapplication.

In the drawings:

Figs. 1 and 2 are side and rear elevational views, respectively, of thevariable pitch propeller di- 35 rected to illustrate the generalarrangement of same.

Fig. 3 is a fragmentary sectional view of the propeller hub portiontaken on the Planes indicated by the staggered line 32 of Fig. 1 and 40illustrating the actuating mechanism for effecting the blade pitchchange; and

,Fig. 4 is a transverse sectional view taken on line 4-4 of Fig. 3.

Referring now to the drawings for a more de- 45 tailed descriptionthereof, the numeral 5 indicates the drive shaft by which the propelleris rotated, the same being secured to the propeller hub 6 by suitablemeans such as that illustrated in Fig. 4. Onto the hub 6 is formed acylindrical 60 casing I, the same. including at its forward en aremovable cover 8.

In the cylindrical wall of the casing I are journaled' a plurality ofpropeller blades 9 preferablysecured for axial rotation in bearingsleeves I! ll integral with the casing 1. The blades I are retained forrotation within the bearings Ill, preferably in the manner shown in Fig.3 in which the blade spindle includes a thrust collar l2 adjustablysecured within the hearing In by a threaded sleeve l3. 5.

The means for rotating each of the propeller blades 9 to effect thepitch change thereof comprises a pull rod l4 extending from within thecasing I and substantially longitudinal to the blade 9, being anchoredat the tip |5 thereof. 10 The pull rod I4 is slidably retained in aslide bearing It, the latter being secured to the blade 9 preferably'atthe widest portion of the-blade and adjacent the trailing edge of same.Each of the pull rods l4 extending to within the casing 15 I thrusuitable apertures H in the wall thereof are pivotally anchored, asindicated at 8, to the end wall of the casing I.-

As hereinafter described, the variation of the blade pitch is effectedby exerting a pull on each 20 of the rods M, which pull is effected bymeans comprising apinion gear l9 disposed centrally in the casing I.'I'he pinion gear I9 is carried on and rotated by a shaft 20, whichshaft extends anally from the drive shaft 5 and is mounted for rotationindependently of same in a central bore of the drive shaft 5. It is, ofcourse, to be expressly understood that the shaft 20 positionedconcentrically within the drive shaft 5 can be moved relatively thereofduring operation of the propeller. That is to say, the shafts 5 and 20during use can be rotated at the same speed or at slightly differentspeeds whereby relative rotation takes place. The actuating means forthe I pull rods I 4 also includes a series of sector gears 2|, each ofwhich is mounted for rotation about a stud 22 secured to the casing 1.Each of the sector gears 2| is formed in an arcuate flange 23 on whichis carried an'internal gear 24. The

. web of each of the sector gears 2| has a cut-out 40 portion 25 topermit the shaft 20 to extend therethru.

It will be observed that the rotation of the pinion gear I9 actuated bymeans of the shaft 20 will impart to each of the sector gears 2| anangular movement. This movement is transmitted to the pull rod H byhaving the mentioned rod secured to the sector gear 2| by means of a lug26 projecting from a corner of the sector gear 2|. The rod I4 is fixedto the lug 26 by a series of clamping elements 21 extending thru thelatter. 1

In considering the operation of the mechanism to effect a pitch changeit will be noted that in view of the eccentricity of the slide bearingl6 l8 on the blade. 8 that the exertion of a substanbetween the point I8and the bearing l6 will be l0 which'the pull rod l4 functions to changethe foreshortenedand in consequence the bearing it will be moved in themanner to cause the rotation of the propeller blade 8.

To return the propeller blade to its normal pitch the pinion gear l9,being reversed, will cause the rod H to be brought to a straight line.form during which the rod' II by a thrust action pushes the hearing I toits normal position. In accordance with the theory of operation by pitchof the propeller. blade 8 the action occur-- ring takes placesubstantially between the hearing l8 and the pivotal anchor ll! of thepull rod I 4. Accordingly, the bearing Ii may be considered as forming afixed connection of the rod be omitted. However, the arrangement illus--ll to an eccentric portion of the blade 9. However, in order that therod ll serve as a reinforcing element to the blade 9, same is arrangedto slide within the bearing I 6 and is extended longitudinally or theblade 9 to be ancho ed at the tip I! thereof. This arrangement is povided so that the rod Il may serve as a strengthening element to theblade 9 by counteracting a centrifugal'force imparted to same during thehigh speed rotation of the propeller.

Referring to Fig. 3, it will be observed that the pivotal anchor ll ofthe rod I4 is substantially adjacent the point of rotation 22 of thesector gear 2| and since the rod llis fixedly secured to a corner ofthe. sector gear 2| by the lug 26, that section of the rod ll betweenthe lug 26 and anchor ll will move in unison with the adjacent edgeof'the sector gear 2| and may accordingly trated is preferred so that inthe event of failure of any of the actuating members preceding the rodM, the latter will merely move to its normal straight line position andthus permit the blade I to return to its normal pitch.

It is to be understood that this improvement is capable of extendedapplication and is not confined. to the exact showing of the drawingsnor to theprecise construction described and,

therefore, such changes and modifications may be made therein as do notaffect .the spirit of the invention nor exceed the scope thereof as, e;-

pressed in the appended claims.

What is claimed as new is:

1. A -.variable pitch propeller comprising in combination, a propellerhub, a series of blades extending from said hub and rotatably mountedtherein, a pull rod for. each of said blades.connected to an eccentricpoint thereof, said pull rods converging to said hub and actuating meansassociated with said hub for tensioning said pull rods so as to rotatesaid blades, said actuating means comprising a rotary pinion-gear and aseries of sector gears in mesh with said pinion gears, each of saidsector gears being operatively connected to one of said pull rods fortensioning the same so as to rotate said blades.

2. A variable pitch propeller comprising in combination, a propellerhub, a drive shaft secured to said hub, a series of blades extendingfrom said hub and rotatably mounted therein, a

pull rod for each of said blades connected to an eccentric pointthereof, said pull rods converging to said hub and actuating meansassociated with said hub for tensioning said pull rods so as. Y

to rotate said blades, said actuating means comprising a' rotary piniongear and a series of secon said hub casing, a pull rod for each ofsaidblades connected to an eccentric point thereof, said 'pull rodsconverging to said hub casing and terminating within same,'and actuatingmeans associated with said hub casingfor tensioning said pull rods so asto rotate said blades, said actuating means comprising a rotary piniongear and a series of sector gears pivotally mounted within said casingand in mesh with said pinion gears, each of said sector gears beingoperatively connected to one of said pull rods for tensioning the sameso as torotate said blades.

PERCY HORROCKS.

